I need to create a third rail at about -1V from an existing dual power supply (+/- 15V for instance). The -1V rail needs to supply up to 50mA but the current demand is not constant.

How do I do this? Can I just use a PNP transistor with the base supplied with the voltage that I would like to achieve, e.g. using a voltage divider between ground and the existing regulated -15V rail as the reference? Also, I should connect the emitter to the -15V rail and the collector to ground?

This seems like a pretty basic valve, but I can't seem to get it to sim correctly.

There is no feedback in this circuit, but I am sure it will deliver a resonably accurate, temperature stable -1V. Simply adjust R1 for the correct output voltage. note, the 220 Ohm resostor in the output pass transistor collector is simply a dissipation limiter.

I noticed this last night after I posted the thread. For some reason I thought the minimum was around -3.5V , but then I read the datasheet.

Since it would be pretty simple to implement, I might just go with an LM337 and live with the -1.2V output. That will probably work just fine for my application.

I am still interested in implementing something like a voltage follower using a transistor, but I have only seen them drawn with a positive source voltage. I can't say that I really know much about transistor circuit design, so I am a bit at a loss. It seems like there should be something using a single transistor that is simpler than the LM337, but I can't come up with it.